Exhaust muffler for engines



Aug. 8, 1961 v. SEIFERT 2,995,200

EXHAUST MUFFLER FOR ENGINES Filed 0m. 25, 1959 2 Sheets-Sheet 1 INVENTOR. VERNON SEIFERT A MK Aug. 8, 1961 v. SEIFERT 2,995,200

EXHAUST MUFFLER FOR ENGINES Filed Oct. 23, 1959 2 Sheets-Sheet 2 IN V EN TOR.

F /ZZ VERNON SEIFERT 7 ATTOP/VEY United States Patent 2,995,200 EXHAUST MUFFLER FO'R ENGINES Vernon Seifert, Box 2235, Anchorage, Alaska Filed Oct. 23, 1959, Ser. No. 848,247 2 Claims. (Cl. 18146) This invention relates to the art of engine exhaust mufflers and particularly concerns a through passage mufller especially adapted for jet engines, high powered reciproeating engines and the like.

One object of the invention is to provide a mufller including a plurality of tubes of different lengths disposed in a parallel and concentric array to provide unobstructed passages of different lengths for exhaust gases.

A further object is to provide a baffle-free mufier for an engine exhaust.

Another object is to provide a muffler having a helical configuration which is curved or straight-sided in cross section, the helical body of the muffler providing a divided expansible outlet for engine exhaust gases.

For further comprehension of the invention, and of the objects and advantages thereof, reference will be had to the following description and accompanying drawings, and to the appended claims in which the various novel features of the invention are more particularly set forth.

In the accompanying drawings forming a material part of this disclosure.

FIG. 1 is a perspective view of one form of mufiler according to the invention.

FIG. 2 is a front end elevational view of the rnufiler of FIG. 1.

FIG. 3 is a longitudinal sectional View taken on line 3-3 of FIG. 2.

FIG. 4 is a side elevational view of another form of muffler embodying the invention.

FIG. 5 is a front end elevational view of the muffler of FIG. 4.

FIG. 6 is a side elevational view of a further form of mufiler according to the invention.

FIG. 7 is a longitudinal sectional view taken on line 7-7 of FIG. 6.

FIG. 8 is a front end elevational view of the muffler of FIGS. 6 and 7 taken on an enlarged scale.

FIG. 9 is a front end view of another mufiler according to the invention.

FIG. 10 is a side elevational view of the mufiler of FIG. 9 with an end portion broken away.

FIG. 11 is a fragmentary view similar to FIG. 7 of another modification.

Referring to FIGS. 13, there is shown a mufier 20 consisting of a plurality of concentrically disposed tubes 21-27. The innermost centrally located tube 21 is longer than the others and extends forwardly furthest. All tubes except tube 27 are transversely aligned at their rear ends and terminate in a common plane 19 short of the rear end of tube 27 to define a free annular sleeve 28 adapted to engage on an exhaust outlet of an engine. Longitudinally extending ribs 30 divide the annular passages defined between the several tubes into sections and serve to hold the tubes in fixed radially spaced array. The mufiler effectively divides a mass of exhaust gas expelled under pressure from an engine into a plurality of streams of different circumferential and axial lengths. This breaks up the sound producing capability of the single gaseous mass by converting it into a plurality of low pressure streams.

The tubes should preferably each have an axial length about one half wave length of the mean frequency of a range of sound frequencies to be attenuated, and each passage should have a circumferential length between ribs 30 of one quarter wave length. Then reflections and Patented Aug. 8, 1961 standing waves will be set up in the tubes which will serve to cancel and silence the sounds of the exhaust gases leaving the several tubes in streams A.

In the form of the invention shown in FIGS. 4 and 5'. the mufller 20 is formed as a helical body. The body tapers to a tubular forward end 32. The rear turn 34 which is the outermost and largest turn of the body is secured to a cylindrical sleeve 36 which serves to secure the muffier to an engine exhaust outlet. The turns of the muflier may terminate in a common transverse plane 38 or the ends may be staggered as shown in FIG. 11. A particular advantage of terminating in a common transverse plane is that the passage 40 for the exhaust gas is so divided that the gas is diverted to travel and expand spirally to follow the circumference of the passage while the gas also travels longitudinally through the mufller. Thus, the gas is divided into a plurality of streams as it enters the several turns of the muffler body and at the same time the gas in each turn can expand in the circumference of the passage as indicated by arrows B. The result is that the original sound pattern of the exhaust gas is disturbed, and the several streams of gas in the muffler turns tend to mix with each other. The resulting turbulence attenuates the sound waves. At the same time the gases are free to move longitudinally in the passage 40 and are discharged after traveling different distances since the several turns have progressively shorter axial lengths from the innermost turn 32 to the outer turn 34.

If the ends are staggered, they peel off the exhaust and stagger the sound waves, straightening out any turbulence at the end. A further advantage of the mufiler structure of FIGS. 4 and 5 is that the several turns are not attached to each other. This permits the walls to flex as the gas under pressure passes through. As a result, gas in one passage may tend to expand or separate the walls of a certain turn while the gas in an adjacent turn is tending to move the walls in an opposite direction. The energy in the several streams of gases is thus spent inopposing movements of the adjacent walls, and the gases leave the mufller in soundless streams.

FIGS. 6, 7 and 8 show a form of the invention similar to that of FIGS. 4 and 5. Mufiler 20 is helical but the several turns 5157 are square in cross section. The passage 46 has the form of a rectangular spiral. The forward turn 51 is axially the longest and narrowest one and terminates with other turns 5256 in transverse plane 38 just inside of the end of outer turn 57. Turn 57 is the shortest axially of the turns. There is thus provided a square sleeve 59 at the rear end of the muffler for securing the same to an engine outlet. The flat walls of the several turns are flexible and can yield to absorb energy from the exhaust gases.

FIGS. 9 and 10 show another form of the invention in which a plurality of groups of tubes 6063 are disposed parallel to each other and secured with a sleeve 65. The center tube 60 is the longest one of the assembly. Around tube 60 is a circular ring of tubes 61 which are axially shorter than tube 60. Around tubes 61 is another ring of shorter tubes 62 and this is surrounded by a further ring of shorter tubes 63-. Sleeve 65 is securely engaged around the outer ring and may be welded thereto. The tubes terminate on a plane 38 which leaves a short cylindrical sleeve portion 82 for engaging the muffler on an engine outlet. This muffler 20 operates like muffler 20 of FIGS. l-3 since a plurality of unobstructed passages are provided at each radial step outward from the axis of the mufiler.

While I have illustrated and described the preferred embodiments of my invention, it is to be understood that I do not limit myself to the precise constructions herein disclosed and that various changes and modifications may be made within the scope of the invention as defined in the appended claims.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent 1. An exhaust mufller, comprising a plurality of concentric t-ubes secured to each other in radially spaced array, an axially disposed one of said tubes being longer than the others, said other tubes being successively shorter axially and having longer radii, and a plurality of axially extending ribs rectangular in cross section secured between adjacent walls of the tubes spacing the same, and dividing the spaces between the tubes into individual passages having arcuate cross sections, the axial lengths of said tubes each being substantially equal to a half wave length of the mean frequency of a range of sound wave frequencies to be attenuated by the tube.

2. An exhaust mufller, comprising a plurality of concentric tubes secured to each other in radially spaced array, an axially disposed one of said tubes being longer than the others, said other tubes being successively shorter axially and having longer radii, and a plurality of axially extending ribs rectangular in cross section secured between adjacent Walls of the tubes spacing the same, and dividing the spaces between the tubes into individual passages having arcuate cross sections, the axial lengths of said tubes each being substantially equal to a half wave length of the mean frequency oi a range of sound wave A frequencies to be attenuated by the tube, and the circumferential lengths of the passages defined between the several tubes and adjacent ribs therebetween being substantially equal to a quarter wave length of the mean frequency of sound wave frequencies to be attenuated in the passage.

References Cited in the file of this patent UNITED STATES PATENTS 734,868 Hill July 28, 1903 1,903,803 Barker Apr. 18, 1933 1,940,790 Diehl Dec. 26, 1933 1,978,678 Kurth Oct. 30, 1934 2,075,316 Tyden Mar. 30, 1937 2,552,615 Baltzer May 15, 1951 2,720,935 Lysholrn et al. Oct. 18, 1955 FOREIGN PATENTS 366,287 Great Britain Feb. 4, 1932 934,030 Germany Oct. 6, 1955 OTHER REFERENCES 

